message-number
The message number of the message to add. The message number for a user-defined message must be 20000 or greater.

message-text
The text of the message to add. The maximum length is 255 bytes. PRINT and RAISERROR recognize placeholders in the message
text. A single message can contain up to 20 unique placeholders in any order. These placeholders are replaced with the formatted
contents of any arguments that follow the message when the text of the message is sent to the client.

The placeholders are numbered to allow reordering of the arguments when translating a message to a language with a different
grammatical structure. A placeholder for an argument appears as "%nn!": a percent sign (%), followed by an integer from 1
to 20, followed by an exclamation mark (!), where the integer represents the position of the argument in the argument list.
"%1!" is the first argument, "%2!" is the second argument, and so on.

There is no parameter corresponding to the language argument for sp_addmessage.